F-Secure has discovered a bug that can cause system crashes on Windows machines loaded with its antivirus software. In real life, the flaw is very rare - only three customer sightings in a year. Today the company has issued a fix.

The flaw involves the way F-Secure Anti-Virus version 5.30 deals with "certain combinations of strange or unusual characters", which can (theoretically) be a problem when a user tries to save a HTML file using Word.

If the file contains complex and long hyperlinks there's a small possibility that it will "blue-screen" a Windows machine running F-Secure Anti-Virus version 5.30.

Although the problem is rare, the impact is potentially severe. F-Secure has made a hotfix available, which addresses the complex filename saving bug, along with other issues.

The Finnish firm urges customers to review its advisory before deciding whether they need to apply the patch. ®